1. Field of the Invention
The present invention relates to a wireless local area network (LAN) and, more particularly, to a method and a device for performing active scanning.
2. Related Art
In recent years, a wireless LAN technology has been chiefly evolved to three directions. There are institute of electrical and electronic engineers (IEEE) 802.11ac and IEEE 802.11ad as efforts for further increasing a transmission rate as an extension of an evolving direction of a wireless LAN according to the related art. The IEEE 802.11ad is a wireless LAN technology using a 60 GHz band. In addition, in order to enable wide band transmission in a distance side as compared with a wireless LAN according to the related art, a wide band wireless LAN using a frequency band less than 1 GHz has been recently spotlighted. Accordingly, there are an IEEE 802.11af using a TV white space (TVWS) and an IEEE 802.11ah using a 900 MHz band. The IEEE 802.11af and the IEEE 802.11ah is mainly aimed at extending in a Wi-Fi (extended range Wi-Fi) service as well as a smart grid and a wide band sensor network. Further, an existing wireless LAN medium access control (MAC) has a problem that an initial link setup time is long in some cases. When the station (STA) performs rapid access to an AP, IEEE 802.11ai standardization activity has been actively achieved.
The IEEE 802.11ai is a MAC technology to achieve a rapid authentication process in order to significantly reduce initial set-up and an association time of the wireless LAN and starts standardization activity as a normal task group in Jan. 2011. In order to enable a rapid access process, the IEEE 802.11ai has discussed about simplification of a process in AP discovery, network discovery, time synchronization function (TSF) synchronization, authentication & association, and a procedure combination with a higher layer. Among them, ideas such as procedure combination using a piggyback of a dynamic host configuration protocol (DHCP), optimization of full extensible authentication protocol (EAP) using a concurrent IP, and an efficient selective access point (AP) scanning are discussed.